Method for insitu anchoring piling

ABSTRACT

Method for securing tubular piling or pile casing in the ground which comprises inserting tubular piling into the ground, preferably heavy piling adapted to be driven into the ground, inserting an expandable mechanism, e.g., an expandable hydraulically actuated mandrel, into the tubular piling at one or more spaced intervals or positions longitudinally along the piling, expanding the mechanism at each such position to expand the piling outwardly to form one or more protrusions spaced longitudinally along the piling, and retracting the expandable mechanism at each such position.

United States Patent [191 Kammeret, Jr.

[451 Mar. 19, 1974 PILING [73] Assignee:

Filed:

Inventor:

Appl. No.:

US. Cl.....

Int. Cl

METHOD FOR INSITU ANCHORING Archer W. Kammerer, Jr., Fullerton, Calif.

Baker Oil Tools, Inc., Los Angeles, Calif.

Dec. 13, 1971 E02d 5/28, B21d 39/00 Field of Search 6l/53.6, 53.68,53.5, 56,

5 References Cited UNITED STATES PATENTS Long. 61/46 Serota 6l/53.6

FOREIGN PATENTS OR APPLICATIONS Great Britain 6l/53.5 Great Britain61/53 Primary Examiner-Jacob Shapiro Attorney, Agent, or Firm-BernardKriegel [57] ABSTRACT Method for securing tubular piling or pile casingin the ground which comprises inserting tubular piling into the ground,preferably heavy piling adapted to be driven into the ground, insertingan expandable mechanism, e.g., an expandable hydraulically actuatedmandrel, into the tubular piling at one or more spaced intervals orpositions longitudinally along the piling, expanding the mechanism ateach such position to expand the piling outwardly to form one or moreprotrusions spaced longitudinally along the piling, and retracting theexpandable mechanism at each such position.

3 Claims, 7 Drawing Figures METHOD FOR INSTTU ANCHORING PILING Thisinvention relates to a method for securing tubular piling in the ground,and is particularly concerned with procedure for inserting tubularpiling, preferably formed of thick wall heavy pipe, in the ground, as bydriving same, and after being inserted to a predetermined depth in theground, forming protrusions at spaced intervals on the piling tosecurely anchor the piling in the ground.

The load-bearing capacity of longitudinally flat or straight tubularpiling is dependent chiefly upon a combination of load-bearing capacityof the soil or ground at the lower end or tip of the piling, and thecoefficient of friction between the ground or soil and the piling skinalong the length thereof. Where the piling is made of metal such assteel, such coefficient of friction may be relatively low and hence amajor portion of the load bearing capacity is dependent upon theload-bearing capacity at the lower end of the piling. Under theseconditions, the cross-sectional area of the piling must be increased,resulting inincreased cost of, the piling and also of its insertion intothe ground.

Continuously corrugated piling, that is pile casing having corrugationswhich extend over the full length of the casing, as illustrated in FIG.1 of US. Pat. No. 3,375,670, similarly utilizes friction between theground and the continuously corrugated skin of the piling, and endbearing loading capacity, to permit loading when inserted into theground. Additionally, the soil trapped between such continuouscorrugations is to some extent mobilized into resistance against itself,but this additional resistance to movement of the pile casing underloading is often insufficient to securely anchor the piling,particularly under heavy loading or when subjected to extreme vibrationor shock loading.

in the above-noted Pat. No. 3,375,670, continuously corrugated lightmetallic tubular casing is inserted into a predrilled hole in soft soil,after which an expanding mechanism is used to expand the casing tosubstantially remove the corrugations and to render the wallssubstantially straight longitudinally. Although this operation increasesthe total volume of the casing and radial pressure is exerted by thecasing against the surrounding soil as a result of this operation, tothereby aid in anchoring the piling, the flattening out of thecorrugations according to this process to render the pile casing againlongitudinally flat or straight, removes the loadbearing resistance ofthe soil initially trapped between the corrugations, and the resultingpile casing again depends for load-bearing capacity in large measureonly upon the coefficient of friction between the soil and the pilingskin.

The above patent states that if desired, the tubular pile casingpreviously rendered flat or straight by the initial expanding operation,can be further expanded by the formation of further corrugations in thewall of the casing after the original corrugations have beensubstantially removed. The resulting re-corrugation produces acontinuously corrugated piling as illustrated in FIG. 4 of the patent.Although the resulting recorrugations are annular in shape rather thanhelical, the re-corrugated pile casing is again essentially acontinuously corrugated piling which in many instances, even with thecompaction of the surrounding soil produced by the initial expansion andthe resistance of the soil trapped in the small areas between theannular re-' corrugations, has a load-bearing capacity which often isinsufficient to securely anchor the piling, particularly against heavyor shock loading or vigorous vibration.

Also, as previously noted, the above patent is directed to securinglight tubular casing in the ground, and which is usually inserted into apredrilled hole. Such light casing cannot ordinarily be driven into theground, except by the use of a mandrel to support it as it is driven, asnoted in the patent. Moreover, such light tubular piling cannot beemployed in many applications for supporting heavy structures andrequiring high loading capacity, and is usually filled with concrete tofinish the pile. i

It is accordingly the object of the present invention to afford a methodof inserting and securing tubular piling, particularly thick heavy walltubular piling, in the ground, and to anchor same in the surroundingsoil against vertical movement therein as result of the application ofhigh static loading, shock loading or high vibrational forces.

There is provided according to the present invention a method ofsecuring tubular piling, preferably formed of thick wall heavy pipe, inthe ground, which comprises inserting tubular piling having straightlongitudinal walls into the ground, eg by driving same, inserting anexpandable means into the tubular piling at one or a plurality of spacedpredetermined positions longitudinally along the piling, expanding suchmeans at each such position to expand the piling outwardly apredetermined extent to form one or a plurality of protrusions orcorrugations extending outwardly at spaced intervals longitudinallyalong the piling, and retracting the expandable means at each suchposition after expansion thereof, to thereby secure the piling againstthe soil of the adjacent ground formation.

The resulting piling with appropriately spaced protrusions orcorrugations extending outwardly to a significant extent, as pointed outin greater detail hereinafter, effectively mobilizes the resistance ofthe adjacent soil, particularly the soil trapped between adjacentprotrusions, against itself over virtually the entire length of thetubular piling with high effectiveness, so that the soil adjacent thetubular piling effectively is in shear against itself throughoutsubstantially the length of the piling, rather thanbeing in shearagainst the side of the piling; The distance between the protrusions orcorrugations, accordingly, is maintained particularly so that theabove-noted condition prevails, that is, so that the angle of shear ofthe soil adjacent the casing is of a magnitude such that the soil is inshear solely with itself substantially along-the entire: length of thepiling between the uppermost and lowermost protrusions on the piling.

According to another feature of the invention, in order to providemaximum effectiveness of the protrusions formed insitu on the pilingaccording to the invention, it has been found that the ratio of theoutside diameter of the piling to the wall thickness of the piling bewithin certain limits, as noted hereinafter.

Generally, the protrusions or corrugations formed at spaced intervalsinsitu on the piling wall have substantially the same configuration andextend outwardly substantially the same amount from. the piling wall,although these conditions can vary as desired, for examplc the extent ofprotrusion of the corrugations can vary, since it is often difficultwhen expanding the piling wall by the expandable means described morefully below, to have each corrugation or protrusion extend outwardlyfrom the piling wall the same amount. Also, the distance betweenadjacent corrugations or protrusions formed on the piling wall can besubstantially the same or can be varied as desired depending upon thesoil conditions encountered.

Also, where formations of different types are encountered along thelength of the tubular piling, for example stratas of sand and clay, onlya portion of the longitudinal length of the tubular piling can becorrugated insitu according to the invention, e.g., where the adjacentformation is of a sandy nature, the remainder of the tubular piling wallremaining longitudinally straight.

The tubular piling is generally formed of metals or metal alloys such asiron, steel, copper, and the like. Any suitable material of constructioncan be utilized which is sufficiently ductile to be expanded to form thespaced corrugations or protrusions thereon according to the invention.

In preferred practice, the tubular piling is inserted into ground havinga high shear strength value relative to its coefficient of frictionagainst the pile surface. Hence the insitu corrugated piling accordingto the invention has high effectiveness in soils having a sandy content,such as sand itself, and particularly in shale. The resistance to axialforces of the insitu corrugated piling of the invention is generally inproportion to the difference between the insitu properties of aparticular soil in shear versus friction against the piling skin. As anillustration, in sand, the insitu piling produced according to theinvention successfully resists pullout forces of about twice the levelof longitudinally straight or flat piling, and substantially higher thenthat of continuously corrugated pile casing of the type illustrated inFIGS. 1 and 4 of above Pat. No. 3,375,670. In shale, the relativedifference in pullout forces between the insitu corrugated piling of theinvention and the straight or continuously corrugated piling noted aboveincreases dramatically in favor of the piling having the spacedcorrugations formed insitu according to the invention, e.g., to theextent of say as much as times the pullout resistance of longitudinallystraight piling.

Any suitable expandable means or mechanism can be employed for insertioninto the tubular piling after it is placed in the ground, for expandingthe tubular piling at one or more predetermined positions along thepiling to provide the insitu corrugations or protrusions on the pilingwall. Thus for example a tool having a hydraulically inflatable mandrelcomprising a short rubber-like packing element can be employed to bulgethe piling outwardly to form the corrugations and the packing retractedby relieving the pressure. Alternatively, suitable mechanical, explosiveor vibrating type tools can be employed for this purpose.

The invention will be more fully understood from a detailed descriptionof certain embodiments thereof taken in connection with the accompanyingdrawing wherein:

FIG. 1 is a longitudinal and partial sectional view of tubular piling inposition in the ground prior to expansion or deformation of certainportions thereof according to the invention;

FIG. 2 is a longitudinal and partial sectional view of the tubularpiling in the ground following expansion of the circumference of thecasing to form the protrusions or corrugations thereon;

FIG. 3 is a longitudinal view partly in cross section of a hydraulicallyactuated tool for insertion into the tubular piling of FIG. 1, to expandthe piling and form the protrusions at predetermined spaced intervals asshown in FIG. 2;

FIG. 4 is a longitudinal view of continuously corrugated tubular casingpositioned in the ground, not in accordance with the invention, but forcomparison purposes;

FIG. 5 illustrates practice of the invention wherein tubular piling isexpanded only in certain locations along the length of the piling;

FIG. 6 is a longitudinal view partly in section of insitu corrugatedpiling in the ground and illustrating a modification of the inventionwherein the distance between adjacent protrusions or corrugations variesand also the extent of bulging of the respective protrusions varies; and

FIG. 7 is a longitudinal view partly in section of step taper tubularpiling having protrusions or corrugations formed insitu thereon afterthe piling is inserted in the ground.

Referring to FIG. 1 of the drawing, tubular steel piling 10 having alongitudinally straight wall 12 is driven into the ground 14 by anysuitable means. The invention is particularly directed to the use ofthick wall heavy tubular piling which can be driven into the groundwithout predrilling a hole therein, and without use of special meanssuch as a supporting mandrel as is required for driving light tubularcasing. Thus, the wall thickness of the tubular piling employedaccording to the invention can range from about three-sixteenths toabout 1 inch. However, tubular piling of smaller or larger wallthickness can be employed, and if desired, a hole can be predrilled inthe ground and the tubular piling dropped therein, or a combination ofthese procedures can be employed, that is the tubular piling can bedriven into a predrilled hole of somewhat smaller diameter, oralternatively, vibrating or circulating techniques can be employed toinsert the piling in the ground.

The outside diameter of tubular piling employed according to theinvention can vary, and can range, e.g. frorn about 6 inches to about 48inches. The invention principles are particularly applicable for tubularpiling wherein the ratio of outside diameter of the piling to the wallthickness ranges from about 25 to about 75.

Generally, and-as illustrated in FIG. 1, the tubular piling is closed byan end bearing 16 at the lower end of the piling, but it will beunderstood that alternatively the tubular piling can be open at bothends and after insertion into the ground, soil or sand trapped withinthe piling can be removed by any suitable means.

A hydraulically actuated expander mechanism illustrated in FIG. 3 islowered into the hollow tubular piling 10 of FIG. 1 to a predeterminedposition therein. The mechanism illustrated in FIG. 3 comprises a hollowcasing 18 carrying a short resilient and inflatable, e.g., rubber-like,packing element 20 around its outer surface. The resilient packingelement is in contact with a plurality of circumferentially spacedplates 23, each carrying an arcuate segment 22, and such plates carryingthe segments 22 are adapted to be movable radially outward on thetubular casing 18. The tubular element 18 is closed at its lower end bya plug 24.

When the expander is lowered into the tubular piling illustrated in FIG.1, the packing element is in normal retracted position around thetubular element 18, and the plates 23 and segments 22 are in thepositions shown in full lines in FIG. 3. Upon passage of a hydraulicfluid under pressure into the tubular element 18 and via a passage 26 inthe casing and into the tubular packer 20, the packer is expandedradially and simultaneously expanding the plates 23 and segments 22 totheir position shown in phantom in FIG. 3, and into compressive contactwith the inner surface of the tubular piling l0, and bulging orexpanding the adjacent circumference of the piling wall 12 to form theprotrusion or corrugation indicated at 28 in FIG. 2. It will beunderstood that the hydraulically actuated cylindrical expanderillustrated in FIG. 3 is simply illustrative of any suitable expandablemeans for expanding the tubular piling to form corrugations orprotrusions therein according to the invention, and hence such expandermechanism forms no part of the present invention.

Following expansion of the expander mechanism to produce the protrusionor corrugation indicated at 28 in FIG. 2, the hydraulic pressure in theexpansion mechanism is relieved, causing the expandable packer 20 andsegments 22 carried thereon to retract to the full line position shownin FIG. 3. The expansion mechanism can then be moved to anotherpredetermined position within the tubular piling and the operationrepeated to form another corrugation or protrusion indicated at 28a inFIG. 2. This operation can then be repeated to form any desiredadditional number of spaced protrusions indicated at 28b in FIG. 2.

The spaced apart protrusions or corrugations as illustrated at 28 28aand 28b in FIG. 2, can have a bulge or outward extension generally of atleast 5 1 inch and usually not more than about 3 inches beyond the outersurface of the tubular piling wall 12, the extent of bulge or expansiondepending on the outside diameter of the piling. Preferably it isdesired to obtain the greatest extent of outward bulging of thecorrugations or protrusions as possible, dependent on the ability of thetubular piling to be deformed without rupturing. The greater the outerextent of the protrusion, the more effectively is the soil mobilizedagainst itself between the adjacent corrugations.

The shape of the corrugations indicated at 28, 28a and 28b is ofgenerally rounded contour as result of expansion of the outer skin ofthe tubular piling by the ex pandable tool in the manner describedabove. In the embodiment illustrated in FIG. 2, the amount of outerradial extension of the respective corrugations is approximately equal,and the distance between adjacent corrugations, e.g., between 28 and28a, between 28a and 28b and betweenthe other successive corrugations,is substantially equal, making for a substantially symmetricalarrangement of the corrugations formed insitu on the tubular pilingwall. This arrangement is preferably employed where the soil conditionsare substantially the same throughout the length of the corrugatedportion of the tubular piling.

As a specific example, but not in limitation of the invention, thestraight sided tubular piling 10 has an outside diameter of 14 inches, awall thickness of 32 inch, and is corrugated according to the inventionas illustrated in FIG. 2, to an outside diameter of 16 inches, that isthe corrugations form an outward bulge of 1 inch from the outer wall ofthe casing, the corruga- -to the invention, the straight sided pilingindicated in F IG. 1, initially driven into sand, moved upon the imposition of a test pull of 47,000 lb. net, whereas the insitu corrugatedpiling illustrated in FIG. 2 and produced according to the inventionmoved upon application of a test pull of 64,000 lb. net.

As previously noted, the spacing between corrugations, say between theadjacent corrugations 28b in FIG. 2, is designed so that the shear angleof the soil, e.g., sand, at the ends of the respective protrusions orcorrugations, and illustrated at A in FIG. 2, is such that the soil isin shear against itself throughout the entire length of the spacebetween corrugations 28b and is not in shear against the side of thetubular piling. This condition is satisfied by spacing the corrugationsso that the shear line 30 of the shear angle A extends from the outerend 31 of one corrugation, e.g., 28b, to the inner end 33 of theadjacent corrugation 2812. In addition, the other angle of shear of thesoil, illustrated at B, adjacent the corrugations 28b is such thatstress is applied along the shear line 32 to a substantially largevolume of adjacent soil 14. It is thus seen that the soil trappedbetween the adjacent corrugations or protrusions of the tubular pilingin FIG. 2 and the adjacent volume of soil effectively mobilizes theresistance of the soil against itself over virtually the entire lengthof the piling, to effectively aid in anchoring the piling securely inthe formation. It has been found that the distance between adjacentprotrusions preferably is about2 to about 30 times the extent of suchprotrusion beyond the outer surface of the piling.

On the other hand, in the case of conventional continuous corrugatedpiling illustrated at 34 in FIG. 4, the small amounts of soil indicatedat 36 and trapped be tween the adjacent corrugations 38, although mobilized into resistance against itself, such resistance is substantiallyreduced due to the small amount of such compacted soil between suchcorrugations and the overlapping of the cones of soil-shear angle fromone corrugation to thenext, as indicated at, 40.

It will be understood that the soil shear angles indicated at A and Bare illustrative and that such shear angles will vary with varyingsoils. Also it will be understood that the invention is not intended tobe limited as to the above-described theory whereby the invention pilingis securely anchored.

Referring to FIG. 5 of the drawing, there are illustrated embodiments inwhich (1) the tubular piling 10a, of a structure substantially the sameas tubular piling 10, has formed insitu thereon according to theinvention principles, only a single protrusion or corrugation 28adjacent the lower end of the tubular piling, (2) a tubular piling 10bagain similar to that of tubular piling 10, with four protrusions orcorrugations 28 spaced apart and located adjacent the lower end of thepiling, and (3) tubular piling 10c, similar to piling 10, having sixcorrugations or protrusions 28 formed insitu at the lower end of thepiling, illustrating :insitu corrugation of only a portion of thetubular piling where the soil conditions at 14 adjacent the insituformed corrugations, e.g., comprising sand, may be different from thesoil conditions of the soil 14a adjacent the upper end of theuncorrugated portion of the respective pilings, e. g., the soil 14a forexample being clay. In clay, which does not freely flow andreconsolidate, as contrasted to sand, and which does not have high shearstrength values relative to its coefficient of friction against thetubular skin of the piling, the insitu formed corrugations according tothe invention are not as effective as in the case of said which has ahigh shear strength value relative to its coefficient of frictionagainst the piling skin.

Referring to FIG. 6, there is illustrated an unsymmetrical arrangementof corrugations or protrusions on the insitu corrugated piling accordingto the invention, wherein the distance between adjacent corrugations 28cand 28d is different from the distance between the adjacent pair ofcorrugatios 28d and 28e. This embodiment is applicable where the soilconditions are different along the various longitudinal locations of thepiling. Also, in the embodiment of FIG. 6, it is seen that the extent ofbulge or outward projection of the corrugations varies, for example,corrugations 280, is smaller than the extent of bulge or outwardprojection of other corrugations such as 28d and 28e. To a large extentthis can be due to the difficulty in expanding each of the spaced apartcorrugations the same amount, by the expandable means employed.

In FIG. 7 there is shown another modification of the invention employingstep taper tubular piling 41 and in which one or more protrusions orcorrugations 28f are formed insitu on one or more of the respective stepportions 42, 44 and 46 of varying diameter, after insertion of thepiling in the ground.

It will be understood that instead of employing an expandable mechanismwhich forms only one corrugation or protrusion at a time, a mechanismcan be employed having multiple expansion elements, e.g., multiplepackers of the type illustrated at in FIG. 3, and multiple sets ofcooperating plates 23 and segments 22 to form a plurality of spacedapart protrusions or corrugations at the same time. However, the use ofatool of the type illustrated in FIG. 3 which forms but a singleprotrusion at a time is preferable, since it permits greater flexibilityin adjusting and varying the distance between adjacent insitucorrugations on the tubular piling.

If desired, following formation of the protrusions or corrugations onthe tubular piling, e.g. in the embodiments of FIGS. 2, 5, 6 and 7, thetubular piling can be filled with concrete, but it will be understoodthat this is not necessary.

The invention procedure can be employed for anchoring tubular pilingsfor suport particularly of heavy structures such as buildings, offshoreoil drilling platforms, dams, and for tying down bridge abutments ofsuspension type bridges.

From the foregoing, it is seen that the invention provides a novelprocedure for inserting and anchoring tubular piling in the ground,particularly where thick heavy wall piling is required. In effect theresult of the invention procedure which produces insitu spaced apartcorrugations longitudinally along the tubular piling is to substitutethe shear strength of the formation itself, e.g. sand, for the shearvalue as between the formation and the piling skin. This results insubstantially increasing the vertical resistance to movement of theinsitu corrugated piling of the invention as compared to smooth oruncorrugated piling or as compared to continuously corrugated piling.

I claim:

1. The method of securing tubular piling in the ground, which comprisesinserting tubular piling into the ground having straight longitudinalwalls and a wall thickness ranging from about three-sixteenths inch toabout 1% inches, inserting an expandable means into said piling,expanding said means against the interior of said piling at intervalsalong the lengths of said piling to form a plurality of external annularprotrusions spaced from each other about 2 to about 30 times the lateralextent of each protrusion beyond the outer surface of said piling andwithout increasing the internal diameter of the piling between saidprotrusions, to thereby secure said piling against the soil of theadjacent ground formation, and retracting said expandable means afterexpansion thereof to enable said means to be moved longitudinally withinsaid piling; said means being expanded against the interior of saidpiling to form said protrusions extending laterally outwardly beyond theouter surface of said piling an amount ranging from about one-fourthinch to about 3 inches, the piling inserted into the ground having anoutside diameter to wall thickness ranging from about 25 to about 75, inwhich protrusions formed by said expanding means are spaced from eachother by a distance such that the angle of shear of the soil surroundingsaid piling and its protrusions is of a magnitude so that said soil isin shear solely with itself substantially along the entire length ofsaid piling between the uppermost and lowermost protrusions on saidpiling.

2. The method as defined in claim 1; in which said piling is insertedinto ground having a high shear strength relative to its coefficient offriction against the external piling surface.

3. The method as defined in claim 1; in which said piling is insertedinto ground comprising sand by driving the piling into said ground to adesired depth.

' 2 133 1 11mm) sm'mss by I l v x w .2 .h I

CL 'QUMCATL O1 (,OlhiiaC'llON Patent No. 3,797,259 Dated March 19, 1914I ,y'iwcntol-(sl fE1 ,L if? M c ab0vc-identifi0d patent that error apears in th ted as shown below:

It is certified aten'i; are hcr eby corrcc and that said Letters P a w I1 Column 5, line, 63: cancel "32''.

- Sigrid and seated this 1st daypf October 1974.

(SEAL) V Attest: f

mccoy'm-clssom JR. c. MARSHALL DANN a Attest'ing Ufficer Commissioner oPatents

1. The method of securing tubular piling in the ground, which comprisesinserting tubular piling into the ground having straight longitudinalwalls and a wall thickness ranging from about three-sixteenths inch toabout 1 1/4 inches, inserting an expandable means into said piling,expanding said means against the interior of said piling at intervalsalong the lengths of said piling to form a plurality of external annularprotrusions spaced from each other about 2 to about 30 times the lateralextent of each protrusion beyond the outer surface of said piling andwithout increasing the internal diameter of the piling between saidprotrusions, to thereby secure said piling against the soil of theadjacent ground formation, and retracting said expandable means afterexpansion thereof to enable said means to be moved longitudinally withinsaid piling; said means being expanded against the interior of saidpiling to form said protrusions extending laterally outwardly beyond theouter surface of said piling an amount ranging from about one-fourthinch to about 3 inches, the piling inserted into the ground having anoutside diameter to wall thickness ranging from about 25 to about 75, inwhich protrusions formed by said expanding means are spaced from eachother by a distance such that the angle of shear of the soil surroundingsaid piling and its protrusions is of a magnitude so that said soil isin shear solely with itself substantially along the entire length ofsaid piling between the uppermost and lowermost protrusions on saidpiling.
 2. The method as defined in claim 1; in which said piling isinserted into ground having a high shear strength relative to itscoefficient of friction against the external piling surface.
 3. Themethod as defined in claim 1; in which said piling is inserted intoground comprising sand by driving the piling into said ground to adesired depth.